Linux MIDI: A Brief Survey, Part 2

In part two of this ever-expanding MIDI series, a look at various sequencers, from Rosegarden to seq24.

Two months ago, I began what I thought
would be a two-part summary of MIDI software for Linux. That plan has
changed somewhat, and this installment actually is Part 2 of what will
be at least a four-part series. This month, I'm your guide to the
world of Linux MIDI sequencers. Next month, I'll
introduce some helpful MIDI utilities. Then, in the final installment,
I'll look at some of the interesting MIDI languages and experimental
environments available to Linux MIDI musicians.

First, a brief review of what a sequencer is and does. Old-school
MIDI musicians would define a sequencer as software or hardware that
records MIDI data entered by way of a performance on a MIDI-enabled
instrument--keyboard, guitar, wind controller--and provides some means for editing
and arranging the recorded data. Remember, MIDI data is not audio data,
and MIDI messages simply give commands to a connected device (hardware or
software) that then should respond according to the particular message.
For example, a MIDI note-on message tells an instrument to play a
specified note, while a stream of pitch bend message tells the instrument to perform a pitch
bend to the specified degree. The range of MIDI message commands is
impressive, and a sequencer can be used to automate a variety of studio
equipment, such as mixers, effects processors and multitrack recorders,
whether tape or digital.

New-school MIDI musicians are more software-based, using softsynths
and plugins in place of racks of external gear. Modern sequencers
also are expected to support audio tracks that can be synchronized with MIDI
tracks. The audio/MIDI sequencer is now the rule: MIDI-only sequencers
still are available, but they have become the exception.

User interfaces for sequencers can take various forms, the most
popular of which include the "piano-roll" coordinate grid system, the
event list and standard music notation. Data may be entered directly
from a MIDI-capable instrument or from the computer keyboard. Once the
data is entered, it may be represented and edited by any or all of the
available user interfaces. Track displays help the musician see the data
in a familiar model adopted from the tape-recording paradigm.

Sequencers also are designed for synchronization with other equipment and
software. MIDI clock and MIDI time code (MTC) messages provide a means
for accurately synchronizing time-critical operations, and MIDI machine
control (MMC) messages can operate the transports and other controls
available on MMC-aware equipment.

Before we go further, I must remind readers that I am not providing
tutorials in these articles. If you want to know more about the programs
presented here, please visit their Web homes and give the software a spin
yourself. Okay, with all that out of the way, let's now look at some of
the available Linux MIDI sequencers.

Rosegarden

Rosegarden is the most mature Linux sequencer, with a development
history extending back to 1993. During the late 90s, Chris Cannam and
Richard Bown decided to update Rosegarden drastically, replacing the aged
Xaw/Motif-like toolkit with the more modern Qt graphics and substantially
upgrading every aspect of the program. The current version of Rosegarden
is a fully modern audio/MIDI sequencer with editor interfaces in all
the expected modes (Figure 1). It offers full sets of the usual MIDI
editing tools, such as various cut/copy/paste functions, data filtering and
substitution routines, block operations and so forth. The program's audio
editing capabilities necessarily are more limited, but you can configure
Rosegarden to summon your favorite soundfile editor for detailed work
on your audio data without leaving the garden.

Figure 1. Rosegarden 0.9.9 in Glory

Rosegarden supports the LADSPA plugin API for its audio processing, and
the most recent versions have incorporated support for the Disposable
Soft Synth Interface (DSSI), an audio programming interface designed
for instrument plugins. DSSI expands Rosegarden's support for software
synthesizers, but its potential as a "LADSPA for instruments" plugin
interface hopefully will appeal to other Linux audio application
developers.

Under the Composition/Studio menu item, you can find Rosegarden's MIDI and
audio device managers. Rosegarden polls your system for available
devices, real and virtual, and maintains its own accounts of their activities
(Figure 2). The program supports ALSA and JACK, but it prefers to set
its connections internally. That is, the user is advised not to use an
external utility such as qjackctl for managing those connections.

Figure 2. The Rosegarden MIDI Device Manager

Once your connections are made, you can proceed to arm a track for
recording by clicking on the small button to the left of the track
name. When you're ready to record, click on the big red record button, and
Rosegarden starts recording whatever comes in through the selected MIDI
input device. After recording, you can edit your performance to perfection
in any of Rosegarden's editors.

Rosegarden has too many features to enumerate or show off here, so you'll
have to visit the Rosegarden Web site to get the full low-down. One of
my favorite aspects of Rosegarden is its ability to export data to the
Csound score format, essentially functioning as a MIDI- or notation-based
front end to that most awesome music and sound programming/processing
environment. Other Linux music and sound applications that support
output to the Csound score format include the Denemo notation-based interface,
the Ceres/Ceres3 spectral domain editors and the Common Music music
programming environment. All these programs are listed on the
Linux soundapps pages.

By the way, Rosegarden's standard music notation capabilities are
excellent, with particularly impressive methods for finessing notation
created from imported MIDI files. Printed output is quite good, and for
users who want the ultimate in printed music output, Rosegarden can export
your work in the
LilyPond music typesetter file format.

During the late 90s, Chris Cannam and Richard Bown decided to update Rosegarden drastically

Rosegarden has three main authors, and it's primarily the other one, Guillaume Laurent, who deserves the credit for kick-starting the drastic update.

Another couple of additions: Rosegarden also supports the JACK transport synchronisation mechanism (mentioned in connection with MusE in the article); and with the DSSI-VST bridge plugin, you can also use Windows VST effects and instruments as plugins in Rosegarden (mentioned in connection with SoftWerk in the article).

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